Over VERY low heat, slowly warm the garlic in the olive oil. Garlic can burn easily when cooked in this manner, so watch very closely. You want to just gently cook until it becomes fragrant. If it turns brown, toss out and start over. Burned garlic is bitter and will ruin the flavor of the dish. (I may or may not have too much personal experience with burning garlic, so just trust me on this one.)

Toss in clean, fresh spinach directly in the pan with the olive oil and garlic. Toss to coat with oil.

Cook the spinach until over low heat, until it has cooked down. It's volume will be reduced dramatically. Add the salt and pepper (to taste). Serve in small bowl and toss with a few splashes of vinegar (if you wish). The dish is delicious without the vinegar as well.